Add rainbow icon

icons/rainbow.json

@@ -0,0 +1,19 @@
+{
+  "$schema": "../icon.schema.json",
+  "contributors": [
+    "danielbayley"
+  ],
+  "tags": [
+    "colors",
+    "colours",
+    "spectrum",
+    "light",
+    "prism",
+    "arc",
+    "clear",
+    "sunshine"
+  ],
+  "categories": [
+    "weather"
+  ]
+}

icons/rainbow.svg

@@ -0,0 +1,15 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M22 17a10 10 0 0 0-20 0" />
+  <path d="M6 17a6 6 0 0 1 12 0" />
+  <path d="M10 17a2 2 0 0 1 4 0" />
+</svg>